Two-cycle engine



Patented Sept. 13, 19,27.

PATENT OFFICE.v

ELMER J'. HART, 0F VANCOUVER, WASHINGTON.

Two-evenel ENGINE.

Application led August 4, 19.28. Serial vNo. 127,105.

My present invention relates generally to two-cycle engines whose most common rdefectl is the lack of thorough exhaust of the burned gases after each explosion and the failure to take in uniform quantities of combustible mixture. The power to be derived from an internal combustion engine of this type is such as to place considerable premium upon uniform operation in the above respects. and it is the primary object of my invention to 'provide such an arrangement als. to promote substantially thorough exhaust or scavenging after each explosion, as well as the supply of a uniform combustible mixture .to the explosion chamber after it hasA been scavenged. l

In the accompanying drawing which illustrates my' present invention and forms a part of this specification Figure 1 is a central vertical sectional view taken through my improved .two cycle enine; g Figure 2 is a similar view taken at right angles to Fig. 1;

Figure 3 is a detail `perspective view of the crank shaft of the charging" and scaveng ing piston, and,

Figure 4 is a detail horizontal section taken substantially on line 4 4 of Fig. 1.

Referring now to these figures my invention purposes a two cycle engine including a cylinder 10 in which a combustion chamber 11 is formed betwen a main piston 12 and a supplemental piston 13, the action of the latter of which will presently appear.

The main piston l2 has a connecting rod 14 leading to the crank 15 of the main crank shaft 16, the latter mounted in one endof the crank portion 17 of the cylinder 10, and projecting 'exteriorly..v thereof at its ends through suitable bearings in order that the crank shaft may receive external operating parts including a ily Vwheel 18 and a make and break ignition device 19.` The ignition device 19 operates in connection with a circuit controlling the firing ofthe charge within the combustion chamber 11. through laY spark plug 20, the` circuit includingv wires= r -21 and 22 and a battery 23. o0 The main piston 12 moves "opposite direction or toward the cylinder ltrapped between vthe piston 13 'and the cyltoward 'the crank case-V portion 17 lof the cylinder 10,

during its power stroke and as it nears the end of-its stroke the piston uncovers the exhaust port through one side-of the cylinder 10 opening into an exhaust pipe 24.

The supplemental piston 13 1s mounted ad- Jacent to the piston or headl end 25 of the cylinder inwardly beyond the intake port of the cylinder which opens into an intake pipe 26 havmg therein a valve 27 closing 1n Va direction away from the cylinder. Moreover the piston 13 has a port therethrough as at 28, controlled by a valve v29, which closes toward the intake port and thus when the piston 13 moves inwardly or toward the main- 65 piston 12, a charge will be sucked into the space between the supplemental piston and the cylinder head 25 through the intake pipe 26. When the piston pipe 13 moves in the 7 0 head 25, the charge previously sucked intol the space between the piston 13 and cylinder head 25 will be forced through the piston port 28, the valve 29 opening to admit the charge which is thus pumped by the piston 13 into the combustion chamber 111. At this time the valve 27 in the intake pipe 26 remains closed by the pressure of the charge` inder head 25. f

It is intended moreover, that the su plemental piston A13 shall move towardp the main vpiston 12 when, nearing the end of its power stroke, the main piston uncovers'the exhaust port, so that in its inward movement toward the main piston 12 the supplemental or charging piston 13 will act to thoroughly scavenge thev combustion chamber by forcing the products oftheprevious combustion outwardly through theexhaust pipe 24. This scavenging movement vof the supplemental piston 13 continues during thecompletion of the power stroke of the main piston 12 and until this piston has'started on its succeeding compression stroke and has reached a point where it is about to again" c lose the exhaust port'. The supplemental piston then quickly' moves in the opposite direction ortoward the cylinder head so as to vforce the charge into the combustion' wl) 35 is rotatable.

' shaft 39 from the position shown in full lines` chamber 11 ahead of the advancing main piston 12. y

lt is for the above purposes that the supplemental piston 13 .is provided with a jointed vconnecting rod upstanding throughthe cylinder or head 25 and connected to the crank 31 of a shaft 32 journal'led through a support 33 mounted on the cylinder head. rlhis shaft 32 has at one end an offset extension 34 on which a collar To the collar 35 is connected one end of a spring 36 whose opposite end is2 anchored to the support 33 for the shaft 3 At its opposite end the shaft 32 has small bevel gear 37 in mesh with a larger bevel gear 38, the latter mounted at the upper end of a shaft 39 journalled ,in bearings 40attached to the cylinder 10, the shaft 39 paralleling the cylinder with its lower end disposed 4adjacent to the main crank shaft 16.

The main crank shaft 16 has an angular outstanding finger 41 located adjacenty to the lower end of the shafty 39 andthe. latter is provided with a pair of diametrically opposed outstanding wings 42, one of which is disposed-in the path of movement of the finger 41, during each revolution of the main crankshaft 16.

The parts are so related that upon each retreating movement of themain piston 12 during the power stroke and. as the main piston 12 uncovers the exhaust port the finger 41 engages one of the wings 42 and rotates shaft 39 through 90 degrees during 'exhaust of the combustion chamber and the initialadvancing movement of the main piston 12 until vit it about to close the exhaust port. During this quarter rotation of the in Fig. 4 tothe position shown in dotted lines, the crank shaft 32 of the supplemental l. piston will be given a `half revolution through the gears 37 and 38 and during this half revolution of crank shaft 32 the supplev mental piston 13 will beadvanced toward the main piston 12. This advancing movement ofthe supplemental piston is thus ac- 'y complished during the completion of the power stroke of the main piston 12 and the initialportion of its subsequent compression stroke orin other words, during the time when the exhaust port is uncovered by thel main piston.

When the crank 31 is turned downwardly at the` end of this half revolution of shaft 32 and as it passes its central lower point, the finger 41 of the main crank shaft 16 ,hav-

v ing turned the shaft 39 from, the position shown in full lines in Fig'. 4 to the position shown in dotted lines, releases from the wing 42 at a time when the spring 36 comes intoA action to draw the o'set extension 34 of A shaft 32 upwardly and thus bring about reimacat treating movement of the supplemental piston 13 as the main piston 12 advances on its compression stroke.

The above cycle is repeated during each` revolution of the main crank shaft 16 and it lis obvious that in view thereof the combusimproved, its operation rendered more stable and its' general effectiveness and efficiency increased.

l claim:

1. A two cycle engine including a cylinder having intake and exhaust ports, main and supplemental pistons located in spaced opposing relationwithin the cylinder, and forming therebetween a combustion chamber, the supplemental piston beinglocated between the main piston and the intake port 'and having means to force a combustible charge from the intake port into the combustion chamber upon its movement in a direction away from the main piston, a crank shaft with which the main piston is connected,` a second crank shaft with which the supplemental piston is connected, a shaft along the cylinder geared at one end to the crank shaft of the supplemental piston and having diametrically opposed outstanding arms adiacent to the crank shaft of the main piston, said latter crank shaft having an angular finger for engagement during the rotation of the crank shaft with one of the arms of the said shaft to rotate the latter and advance the supplemental piston toward the main piston, and spring means engaging the crank shaft of the supplemental piston for shifting the latter away from the main piston whereby the'complete stroke of the supplemental piston will be occomplished vduring a portion of the stroke of the-main lpiston.

2. A two cycle engine including a cylinder i 'having intake and exhaust ports, main and diametrically opposed arms adjacent to the crank shaft of the main piston, said latter crank shaft having a inger for engagement with one of the arms of the crank shaft to rotate the later and advance the supplemental piston toward the main piston, and spring means engaging the crank shaft of the supf plemental piston for shifting the supplemental piston away from the main piston whereby the complete stroke of the supp1e. 10

mental piston will be accomplished durlng a portion of the stroke of the main piston.

ELMER J. HART. 

